Indicator for cartridge-fuses.



, S.'W. HUFF.

INDICATOR FOR CARTRIDGE FUSES.

APPLICATION FILED AUG.2I. I914.

1,301,848. Patented Apr. 29,1919.

SLAUGHTER W. HUFF, F BROOKLYN, (NEW YORK.

INDICATOR non canrnmen-rusns.

Specification of Letters Patent.

Patented 'Apr; 29, 1919.

Application filed August21, 1914. Serial No, 857,903.-

' To all whom it may concern:

to having a portion of the subsidiary wire Be it known that I, SLAUGHTER W. Herr, a citizen of the United States, residing in the borough of Brooklyn, in the city and State of New York, have invented certain new and useful Improvements in Indicators for Cartridge-Fuses, of which the following is a specification.

This invention relates to electric fuses to be introduced into an electric circuit for limiting the current that can be fed to instruments and thus protect them from an overload; and particularly to so-called cartridge fuses Where the fusible linkis incased and embedded, so that itbecomes necessary to provide an indicator to show when the fuse has been blown. Various expedients have been suggested, such as the-provision of a subsidiary conductor within the case and in conductive relation to the fuse terminals, so that it is destroyed whenever the main fuse link is blown; this subsldiary conductor being rendered visible either through a reduced opening in the case, or by bringing a portion of 1ts length on the surface of the case; or its fusing being rendered manifest by causing it to discolor'a chemically prepared label, either directly by I its own heat or through the medium of a slowly combustible substance; or in someinstances by causing the gases of its fusion to disrupt a covering piece applied to the case. But these methods are uncertain and unsatisfactory, because not positive enough in their effects, or because of the ob]ect1on exposed. According to the present invention, the subsidiary wire is retained wholly within the case, and a diminutive gun is formed in the wall of the case in such relation to said wire as to be discharged by the fusing of the wire; a breech closure in the form of a piece of fiber or other suitable material being provided on the inner wall of the casing and as a means for holding the subsidiary wire in place, while a charge of (preferably) smokeless powder is introduced in the bore formed in the case and confined by a wad of plastic material, such as plaster of Paris, which is readily displaced and the absence of which becomes the telltale. or indicator when the fuse blown.

The invention will be fully understood upon reference to the illustrative embodiment disclosed in the accompanying draw- 1ng, 1n which- Flgures 1 and 2 are axial longitudinal sections of a fuse embodying the present in vention,,showing, respectively, the condition before blowing and the condition after blowmg.

Fig. 3 is an end view of the fuse.

1 represents a tubular casing preferably of fiber, 2 the main fuse link embedded and incased therein, 3 the end caps by which the.

or indicator wire which is laid along the. ins ner wall of thecasing and has its ends laid over the ends of the casing as at 4 in posit1on toremain in electrical contact with the end caps 3. y i

According the operative theory of the present lnvention, a means is provided of definite form and location which is adapted byits presence to indicate thefact that the fuse remains intact and vby its absence the fact that the fuse-has been blown. This means'consists of a wad 8 fitting a'bore 5 in the wall of the casing and preferabl made of some plastic material which can conveniently and cheaply molded in place, and in order that it may be displaced by conditions indicating an overload of the fuse and impairmeht of its main conducting link, the bore carries beneath the wad 8, a charge 6 of explosive, preferably smokeless powder.

Inorder to ignite this powder, either by a sudden fusing of the subsidiary wire or by a gradual heating up to the fusing point, the

wire 4 is laid diametrically across the inner end of the bore 5 and the bore is backed u and the wire held in place by a breec closure 7 underlying the inner surface of the casing and comprising a strip sufficiently substantial. to cause the out ard dischar e -of the powder when. ignited, particular y be distinguished not only by the eye when the fuse is plainl 1 visible, but by the sense of touch where the ocation of the fuse does not present it plainly to view. By comparing Fig. 1 with Fig. 2, it will readily be seen that Figr 1 presents a condition which to the eye will readily indicate that the fuse has not been impaired, particularly if the plastic material forming the wad 8 is plaster of, Paris or some other substance readily contrastin with. the color ofthe casin and it wil indicate this condition readi y to the sense of touch because of the comparative evenness of the'surface when the wad is in place, but when the bore-5 is entirely empty, as shown in Fig; 2., the condition is appreciated with equal readi ness both to the eye and the touch.

The plaster of Paris or equivalent material is advantageous for the further reason'that it provides a substantially. impervious closure,

for the bore which; on the one h'andjconfines the gases of the propelling charge until sufficient to drive the projectile furnished by the wad, and on the other hand protects the comparatively light explosive charge from dampness or other deteriorating influences;

. A still further advantage of a plastic closure for the bore is the cheapness in cost of labor and material with which it can besulpplied, it merely being necessary to wipe t e material in plastic state ac ross'themouth of the hore to insure insertion and accuratefit'ting;

The breech closure 7 will be secured in position by any suitable means, as for'instance furnace cement. This means of securing the breech closure not onlypositions the strip until the filler can be packed into the casing, but it efiectively seals the breech end of the bore around the wires, as well as between the pposed faces of the strip and the "casing,

I claim i In an indicator fusehaving two end caps,

an inclosing case having an openin in the wall thereof, a breech closure for t e inner end "of said opening, a charge of explosive substance in the opening near the inner end SLAUGHTER W. HUFF.

, In presence of HELEN SEenmaAcnER, JOHN A. THAKE. 

